Induction Drugs - Etomidate Exam 2 Flashcards
What is the mechanism of action of etomidate?
binds to GABA-A receptors
open Cl-channels
cell hyperpolarization
What is unique about Etomidate’s organic chemical structure?
It is the only carboxylated imidazole containing compound.
What is the induction dose for etomidate?
0.3 mg/kg IV
What is the onset and peak of etomidate?
- Onset: 1 min
- peak: 2 mins
what is the half-time of etomidate?
2-5 hours
At what pH is etomidate water-soluble vs lipid-soluble?
- weak base drug
- water soluble = acidic pH
- Lipid-soluble = physiologic pH
What percentage of etomidate is propylene glycol? What is the result of this?
35% propylene glycol = pain on injection
What is an alternative route for etomidate administration? Benefits of this?
- Sub-lingual etomidate
- bypass hepatic metabolism
Why does etomidate have a low incidence of myoclonus?
Trick Question. Etomidate has a high incidence of myoclonus, just like all other induction agents.
How much of it is protein bound? What protein does it bind to?
- 76% albumin
What is etomidate’s Vd? How does clearance compare to thiopental? What is the result of this clearance?
Large Vd
5x faster > thiopental = prompt awakening.
What metabolizes etomidate? What is the elimination profile?
- CYP450
- plasma esterases
- 85% via urine, 10-13% via bile
- no cummulative drug effect/no hangover
What is the best use for etomidate?
- Induction for unstable cardiac patients. (Minimal changes to HR, SV, CO, contractility)
- Good choice for low EF
- alternative to propofol or barbiturates for induction
What needs to be used concurrently with etomidate when performing a laryngoscopy? Why?
Opioids
etomidate has no analgesic effects.
What is Etomidate’s most common side effect? How often does this occur?
- Involuntary Myoclonic Movements
- (50 - 80 %) of administration
List in order the probability of myoclonus side effect: etomidate, thipoental, propofol, and methohexital.
- Etomidate 50-80%
- Thipoental 17%
- Methohexital 13%
- Propofol 6%
What can be administered with etomidate to prevent myoclonus?
- Fentanyl 1-2 μg/kg IV
- benzodiazepines
- (use caution in patients with seizure history)
Etomidate has a dose dependent inhibition of the conversion of cholesterol to _________. What does this mean clinically?
- Cortisol
- adenocortical suppression = inhibits natural stress response
- severe hypotension, longer on vent
How long does adrenocortical suppression with etomidate last?
What two pathologies would cause you to hesitate before giving etomidate?
4 - 8 hours.
Sepsis & hemorrhage (anything where you need an intact cortisol response).
how does thiopental and etomidate compare in cortisol regulation?
- Etomidate = decrease in plasma cortisol
- thiopental = no decrease in plasma cortisol
What are etomidate’s effects on CBF & CMRO₂?
↓CBF & ↓CMRO₂ 35-45%
What effect does etomidate have on cerebral vessels and ICP?
- Direct cerebral vasoconstrictor
- ↓ICP
CMRO₂ is coupled with both CBF and _______.
CMRG (cerebral metabolic requirement of glucose)
What is the EEG profile of etomidate?
- More excitatory than thiopental
- May activate seizure foci
- may increase amplitude of SSEP
